humanize_number(3) - NetBSD Manual Pages

HUMANIZE_NUMBER(3)      NetBSD Library Functions Manual     HUMANIZE_NUMBER(3)


NAME

     dehumanize_number, humanize_number -- format a number into a human read-
     able form and vice versa


SYNOPSIS

     #include <stdlib.h>

     int
     dehumanize_number(const char *str, int64_t *result);

     int
     humanize_number(char *buffer, size_t len, int64_t number,
         const char *suffix, int scale, int flags);


DESCRIPTION

     The humanize_number() function formats the signed 64 bit quantity given
     in number into buffer.  A space and then the suffix (if not null) is
     appended to the end.  len gives the size of the buffer.

     If the formatted number (including suffix) would be too long to fit into
     buffer, then repeatedly divide number by 1024 until it will fit.  In this
     case, prefix suffix with the appropriate SI designator.

     The prefixes are:

           Prefix    Description    Multiplier
           k         kilo           1024
           M         mega           1048576
           G         giga           1073741824
           T         tera           1099511627776
           P         peta           1125899906842624
           E         exa            1152921504606846976

     len must be at least 4 plus the length of suffix, in order to ensure a
     useful result is generated into buffer.  To use a specific prefix, spec-
     ify this as scale (Multiplier = 1024 ^ scale).  The scale must be at
     least 0 and no more than 6.

     Alternatively, one of the following special values may be given as scale:

           HN_AUTOSCALE  Format the buffer using the lowest multiplier possi-
                         ble.

           HN_GETSCALE   Return the prefix index number (the number of times
                         number must be divided to fit) instead of formatting
                         it to the buffer.  That is, the scale that would have
                         been used if HN_AUTOSCALE had been used.

     The following flags may be passed in flags:

           HN_DECIMAL    If the final numeric result is less than 10, and is
                         not the same as the original value (that is, it has
                         been scaled) display it using a decimal radix charac-
                         ter, and one following digit.

           HN_NOSPACE    Do not put a space between number and the prefix.

           HN_B          Use 'B' (bytes) as prefix if the original result does
                         not have a prefix.

           HN_DIVISOR_1000
                         Divide number with 1000 instead of 1024.  That is,
                         use decimal scaling instead of binary.

     To generate the shortest meaningful value, a buffer length (len) that is
     6 greater the length of the suffix along with HN_AUTOSCALE will ensure
     the highest meaningful scale is used.  Allow one extra byte for the sign
     if the number is negative, and one less if the HN_NOSPACE flag is used.

     The dehumanize_number() function parses the string representing an inte-
     gral value given in str and stores the numerical value in the integer
     pointed to by result.  The provided string may hold one of the suffixes,
     which will be interpreted and used to scale up its accompanying numerical
     value.


RETURN VALUES

     humanize_number() returns the number of characters stored in buffer
     (excluding the terminating NUL) upon success, or -1 upon failure.  If
     HN_GETSCALE is specified, the prefix index number will be returned
     instead.

     dehumanize_number() returns 0 if the string was parsed correctly.  A -1
     is returned to indicate failure and an error code is stored in errno.


ERRORS

     dehumanize_number() will fail and no number will be stored in result if:

     [EINVAL]           The string in str was empty or carried an unknown suf-
                        fix.

     [ERANGE]           The string in str represented a number that does not
                        fit in result.


SEE ALSO

     strsuftoll(3), orders(7), humanize_number(9)


HISTORY

     humanize_number() first appeared in NetBSD 2.0.

     dehumanize_number() first appeared in NetBSD 5.0.

NetBSD 10.99                    March 11, 2019                    NetBSD 10.99